Mercury switch



July 17, 1962 C. A. ELLIS MERCURY SWITCH Filed Sept. 21, 1959 United States Patent O 3,045,083 MERCURY SWITCH Charles A. Ellis, Marion, Mass., assigner to Glass-Tite Industries, Inc., Providence, RJ., a corporation of Rhode Island Fired sept. 21, 1959, ser. No. 841,381 4 Claims. (Cl. Mtl-152) The present invention relates to an electric switch. More particularly, the present invention relates to an electric switch that includes a rotatable liquid contact circuit controller.

Electric switches that employ a noiseless liquid contact circuit controller have been in use for some time and have been found to be generally acceptable for normal operations. However, `after extensive use it has been found that the operating mechanism thereof is caused to wear unduly thereby resulting in faulty contact between the liquid contained in the circuit controller and the electrical contacts. Prior to the instant invention the prior known liquid circuit controlling devices have generally included a metal container or receptacle defined by cupshaped metal terminals separated by an annular glass bead and provided with an insulating barrier disposed between the cup-shaped terminals. ln these prior known devices a pool of mercury was disposed within the cupshaped terminals so that upon rotation of the container to the on position, the mercury caused electrical contact to be made between the cup-shaped terminals.

The present invention avoids the inherent defects found to be present in these prior known devices and provides a novel electric switch that includes a rotatable capsule having a body of mercury deposited therein together with a well member. The well member, which is formed of an insulating material, has an electrode extending outwardly therefrom and is arranged such that upon rotation of the capsule a small pool of mercury disposed within said well is adapted to communicate with the larger body of mercury loca-ted Within the capsule. Thus, a mercuryto-mercury make and `break switch is provided which insures longer life of the switch and more positive action of the switch in operation.

lt is, therefore, an object of the present invention to provide an electric switch utilizing a liquid contact circuit controller.

Another object of the present invention is to provide an electric mercury switch which includes a capsule having a well member positioned therein for creating a mercury-to-mercury make or break action.

Still another object of the present invention is to provide a mercury electric switch which is positive in action and which includes a unique form of an electrode or contact member that cooperates with the well member Within the capsule to close the circuit between Ithe electrical contacts o-f the switch.

Still `another object of the invention is to provide a mercury switch having a capsule formed with an electrode extending outwardly therefrom for making electrical contact with a contact member.

With the foregoing and other objects in view, the invention will `be more fully described hereinafter, and will be more particularly pointed vout in the claims appended hereto.

in the drawings, wherein like symbols refer to like or corresponding parts throughout the several views:

FIG. l is a front elevational View of the electric switch embodied in the present invention;

FIG. 2 is a sectional view of the electric switch taken along lines 2-2 in FIG. l and illustrating the on positio-n of the switch;

FIG. 3 is a sectional view similar to FIG. 2, illustrating the switch inthe oit position;

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FIG. 4 is an enlarged view of the operating button and capsule `assembly showing the mercury-to-mercury contact within the capsule well when the switch is disposed in the on position;

FIG. 5 is an enlarged view yof the operating button and capsule assembly similar to FlG. 4, showing the location of ythe mercury within the capsule when the switch is disposed inthe oil position thereof; and

FlG. 6 is a sectional view taken along line 6 6 of FIG. 4.

Refer-ring now to the drawings, `and more particularly to FIGS. l through 3, the mercury switch embodied herein is generally indicated -at lil and includes a mounting strap l2 having openings 14 formed at opposite ends thereof, lthe openings 14 `being adapted to receive a screw or other fastening element (not shown) for mounting the strap in position in a recess formed in a wall or the like. The mounting strap l2 further includes -a rectangularlyshaped opening i6 formed centrally thereof which is adapted to receive therethrough the operating button of the switch. Formed on the marginal portions dening the opening i6 are arcuate shaped portions 17 that limit the movement of the operating button as will be described hereinafter.

Secured to the mounting strap 12 by screws 18 which extend through suitable openings formed in the mounting strap is a body member 2li, the rearmost portion of which projects into the recess of the wall on which the switch lli is mounted. As shown in FIG. 2, the body member 2d is formed in a shell construction, preferably of molded plastic, and includes oppositely positioned outwardly extending recessed ears 22 and 24 (FIG. l). Formed in each of the ears 22, 24 is a recess 25 that receives a terminal screw 26 therein. The terminal screw 26 threadably extends through :an opening rformed in a contact head 2S, the contact head 28 being formed integral with a longitudinally extending contact member 30. A contact member 32 (FIG. 6) is formed similarly to contact member Sil and includes a contact head that receives a terminal screw that in turn extends into a recess formed in the ear 24. It will be understood that contacts 30 and 32 are of identical construction except that they are reversely disposed and extend adjacent opposite sides of body 20 so that their respective contact heads can engage ears 22 and 24 in the manner indicated.V l

As shown in FIGS. 2 Iand 6, the contact members 30, 32 extend substantially the length of the interior of the body member 2t) and are in spaced parallel relation with respect to each other. Enlarged central portions 33 of the contact members `are dished to define bearing surfaces for rotatably receiving a capsule generally indicated at 34. The capsule 34, which denes the liquid contact circuit controller of the subject invention, is formed in a generally tear-drop shape, as seen in cross section in FIGS. -2 and 4, and includes a metallic cap 36 formed with a peripheral llange 38 (FIG. 6). Joined to the flange 3S as by welding or the like and enclosing the cap V36 isa plate 40 having a central opening 42 formed therein. A seal 44 is positioned Within the opening 42 and is adapted to rigidly receive therethrough, in .sealing relation therewith, an arm of an electrode to be described hereinafter.

Located within the capsule 34 and positioned at the narrow portion of the tear-drop section is a well 46. The well 46 is formed of a non-metallic, non-corrosive material, such as ceramic, and includes a chamber 48 in which a small pool of mercury 5i) is disposed. The chamber 48 is detincd by a rear wall 51, side walls 52 and a foreshortened front wall 53. The foreshortened front wall 53 prevents the small pool `of mercury 50 from ilowing out of the well in the oli position of the switch, as shown in FIG. 5. The side walls 52 of the well are snugly positioned between the rear wallet the cap 36 and plate 40 Patented July 17, 1962V to insure make or break acta-css and the well is maintained in position so that, as the capsule is rotated, the foreshortened wall 53 will either extend above or below a pool of mercury 54 disposed within `the capsule but outside the well. In the off position of the switch, the level of the larger or major body of mercury 54 disposed within the capsule 34 extends below the upper edge of the foreshortened wall 53; thus, the body of mercury 54 is prevented from communicating with the chamber 48 of the well 46 and the small pool of mercury 50 disposed therein. As illustrated in FIG. 4, when the switch is moved to the on position, the tear-drop shaped capsule is rotated clockwise, the narrow portion of the tear drop moving downwardly to cause the well 46 to be tilted. In this position, since the larger or major body of mercury 54 remains in a horizontal or level position, the level thereof extends above the upper edge of the wall 53, and the mercury 54 thus iiows over the top edge of the foreshortened wall 53 and into the chamber 48. The mercury 54 thereby intermingles with the pool of mercury t) anda mercury-to-mercury contact between the body of mercury 54 and the small pool of mercury 50 is effected. It is seen that the pools of mercury 50, 54 will `be caused to communicate with each other with only a slight rotary movement of the capsule 34, and, in practice, the large pool of mercury will liow over the wall 53 after rotation of the capsule 34 of approximately 5 degrees. It has been found that in order with this relatively slight rotary movement of the capsule, the ratio by volume of mercury S4 to pool 50 is at least 10 to 1. It will be understood, however, that a lesser ratio could exist but that it would then take a greater degree of rotation to effect make and break of the switch.

In order to rotate the-capsule 34, the capsule is formed with `an outwardly dished portion 56 on the bottom wall of the cup member 36, the outwardly dished portion 56 making 4bearing contact with the corresponding dshed portion 33 of the contact element 32. An electrode 58 is disposed within the well 46 and extends upwardly therefrom, being formed with an arm 60 that is joined to the portion that extends within the well at right angles with respect thereto. Another arm 62 of the electrode is joined to. the arm 60 at right angles thereto and extends through the seal 44. The arm 62 has a contact button 64 secured to the end thereof which is formed with a convex outer face that cooperates with the dished portion 33 of the contact member 30. As illustrated in FIG. 6, the dished portion S6 and the contact button 64 mount the capsule 34 for rotation between the contact members 30 and 32.

It will be understood that the securement of ange 38 to plate 40 effects an air-tight seal therebetween, while at the same time the seal 44 is air tight, whereby the capsule is effectively hermetically sealed. This, of course, is important in mercury switches of this type in order to prevent undesirable arcing between the pools of mercury when the switch is in its off position. Also, it will be noted that the electrode 58' and capsule 34 are not relative'l'yrotatablewith respect to each other but rather rotate as a unit between the aforedescribed bearings 33. Thus, the depending arm of electrode 58 which extends into the well 46, and which fits snugly therein between side walls 52 and against rear wall 51 (FIGS. 4 to 6), functions to maintain the well securely in position within the capsule, thereby rendering any additional securement between the well and the capsule unnnecessary.

The capsule 34 is adapted to `be rotated in the body member by an operating button generally indicated at 70, the operating button 7 0 including a handle portion 72 to which an arcuate shaped body 74 is integrally joined. Theunderside of the body 74 is formed with arcuate surfaces 76, 78 (FIG. 6) which are spaced apart to define anarcuate shaped groove 80 therebetween, the groove 80 receiving the flange 38 of the capsule 34'and the plate 40 therein. Joined to the sides of the body 74 extending outwardly therefrom and following the arcuate contiguration thereof are anges S4, one of which is shown in FIGS. 2 and 4. Formed on the flanges 84 are projections 86 which, as shown in FIG. 2, in the assembled position of the switch are positioned within the arcuate portions 17 of the strap 12 and cooperate therewith to define the limit of movement of the operating button 70. The operating button is adapted to positively engage the capsule 34 for imparting rotating movement thereto by means of a projection 88 formed on the underside of the arcuate surface 76. The projection 88 extends into a recess 90 formed in the wall of the cap 36 and, as seen in FIGS. 4 and 6, is held in snug engagement therein by the coaction of the arcuate surface 76 of the body 74 in engagement with the curved wall of the cap. It is seen that rotation 4of the operating button 70 will cause the capsule mem-ber 34 to rotate therewith, the limit of movement being predetermined by the movement of the projections S6 within the arcuate portions 17 of the strap 12. Although the arcuate portions 17 define the limit of movement of the operating button 70, it only takes approximately 5 degrees of movement thereof to break contact between the mercury pools.

In operation, when the mercury switch is located in the off position, as seen in FIG. 5, the handle portion 72 of the operating button 70 is pointing downwardly. In this position, the small pool of mercury 50 is prevented from making contact with the larger body of mercury 54 by the barrier defined by the shortened wall 53 formed on the front of the well 46. When the handle portion 72 is moved upwardly to the position shown in FIG. 4, the larger body of mercury 54 is caused to flow over the wall 53 and into communication with the interior of the well 46, thereby making contact with the small pool of mercury S0. Electrical contact is thereby established through the contact member 30, electrode 58, mercury bodies 50, 54, the cap 36 and the contact member 32.

It is seen that the present invention provides a mercury switch that is simple in construction, effective in operation, and inexpensive to manufacture. The mercury-tomercury make and break operation insures a longer life of the switch, reduces arcing and provides for rapid make and break between the contact elements.

It will be obvious to those skilled in the art that various changes may be made without departing from the spirit of the invention and therefore the invention is not limited to what is shown in the drawings and described in the specification, but only as indicated in the appended claims.

What is claimed is:

l. In an electric switch, a liquid contact circuit controller rotatably mounted within a body, said circuit controller comprising a hermetically sealed capsule of conductive material, a well formed of non-conductive material located within said capsule, a first body of mercury located within the conductive capsule outside of but adjacent said well, a second body of mercury within said well, an electrode extending through said capsule from the exterior thereof into contact with the interior bottom of said well and said second body of mercury, said electrode being electrically insulated from said capsule as it passes therethrough and engaging said well so as to hold the latter firmly in place within said capsule, and a pair of spaced contact members, one of said contact members making engagement with the outer surface of said capsule and the other of said members making engagement with the outer end of said electrode, whereby when said controller is rotated to a first position, said first and second bodies of mercury are caused to merge with each other to complete a circuit from said one contact, through the electrode, through the merged bodies of mercury, and then through the capsule to said other contact, whereas when said controller is rotated to a second position, the said bodies of mercury are separated from each other to interrupt the circuit.

2. The switch of claim 1 further characterized in that said capsule is of substantially tear-drop configuration, said well being positioned at the pointed end of said conguration and having side walls, a bottom wall and a rear wall, the entire outer surfaces of said walls making snug engagement and contact with the inner surfaces of said capsule, said well further having a 4foreshortened front wall extending upwardly from said lbottom wall for separating `the bodies of mercury when the switch is in its said second position.

3. The switch of claim 1 further characterized in that said capsule is provided With an outwardly extending roundedsprotuberance, said one contact having a dished portion receiving vsaid protuberance in bearing relation, said electrode having at its outer extremity a rounded conductive button, said other Contact having a dished portion receiving said button in bearing relation, whereby said controller is rotatably journalled between said spaced contacts.

4. The switch of claim 1 further characterized in that the ratio of potential flow volume of said irst body to said second body is at least 1() to 1 when the circuit controller is at the position of circuit interruption.

References Cited in the le of this patent UNITED STATES PATENTS 

1. IN AN ELECTRIC SWITCH, A LIQUID CONTACT CIRCUIT CONTROLLER ROTATABLY MOUNTED WITHIN A BODY, SAID CIRCUIT CONTROLLER COMPRISING A HERMETICALLY SEALED CAPSULE OF CONDUCTIVE MATERIAL, A WELL FORMED OF NON-CONDUCTIVE MATERIAL LOCATED WITHIN SAID CAPSULE, A FIRST BODY OF MERCURY LOCATED WITHIN THE CONDUCTIVE CAPSULE OUTSIDE OF BUT ADJACENT SAID WELL, A SECOND BODY OF MERCURY WITHIN SAID WELL, AND ELECTRODE EXTENDING THROUGH SAID CAPSULE FROM THE EXTERIOR THEREOF INTO CONTACT WITH THE INTERIOR BOTTOM OF SAID WELL AND SAID SECONG BODY OF MERCURY, SAID ELEC TRODE BEING ELECTRICALLY INSULATED FROM SAID CAPSULE AS IT PASSES THERETHROUGH AND ENGAGING SAID WELL SO AS TO HOLD THE LATTER FIRMLY IN PLACE WITHIN SAID CAPSULE, AND A PAIR OF SPACED CONTACT MEMBERS, ONE OF SAID CONTACT MEMBERS MAKING ENGAGEMENT WITH THE OUTER SURFACE OF SAID CAPSULE AND THE OTHER OF SAID MEMBERS MAKING ENGAGEMENT WITH 